Jason Citron (founder of Openfeint and Discord) Sold his company in 2011 to GREE. Around the same time Openfeint was involved in a class action lawsuit with allegations of scraping personally identifiable information from user interactions and reserving the right to sell it, among other related allegations.
There are many sources for this if you'd like to do some digging. Here are a few that covered the story, the complaint, and a video from a chap that will probably be more helpful than I could be in a reasonable amount of time.
Business buy over:
https://www.mcvuk.com/business/openf...der-steps-down
articles about the case:
https://archive.org/details/OpenfeintComplaint
https://www.adweek.com/digital/openfeint-lawsuit-gree/
https://en.wikipedia.org/wiki/OpenFeint
Perhaps more helpful to some, video
https://archive.org/details/youtube-QN_6AZT92pU
As far as I can see the case was voluntarily dismissed, likely due to the actions being within the scope of the End User Agreement, but that of course doesn't make the actions right.
Discord, a company founded on the principle of keeping their communication software "free", obviously needs to cover running costs. Over and above that, they have received large investments in the tens of millions, some of which include $20 million dollars from a venture capital firm called Greylock partners and a further $50 million more recently from a group of investors including the same again.
Venture capitalists take calculated risks based on existing value growing over time. The most valuable thing in Discord it's user base. I hope you can see how I (and many others) could find it hard to place their trust in a project with this kind of history, where the valuable asset is the same as has been abused in the past.
Riot on the other hand is FOSS (Free Open Source Software), allowing anyone to read and see what is being done by the software. If it were to be engaging in the same kind of data capture, you could read where it does this and (if you were so inclined) remove that functionality, improve it and start your own Opensource fork that doesn't scrape personal data. Also with the network being decentralised there is no one place that data would be captured and exploited from since you control which server you create your account in.
On top of that, being able to self host goes a step further toward helping make sure my data isn't being stored somewhere I don't want it to be.
Sure, the network can be slow if you connect yourself to high traffic channels but if you don't it works well and is being actively worked on.
A long post, but an important issue.